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Series of missteps led to fatal crash of ACE flight 51

National Transportation Safety Board investigator Brice Banning at the site of an ACE Air Cargo plane crash near Dillingham in March 2013.
NTSB photo

The National Transportation Safety Board amassed a file of more than 300 pages of documents while investigating the fatal March 8, 2013 crash of Alaska Central Express flight 51. These documents support the probable cause findings released by the NTSB earlier this month, but they also provide insight to a long series of events that led to the accident.

The captain of the flight, Jeff Day, had 5,770 hours of flight time, 5,470 of it in the Beech 1900, the type of aircraft involved in the accident. He had been with the company since 2008 and upgraded to captain in 2011. Co-pilot Neil Jensen had 470 flight hours, 250 of which were in the Beech 1900 and was hired on Nov. 30 of 2012.

Flight 51 departed Anchorage about 5:45 a.m. and was routed to King Salmon, Dillingham and return. Light rain and snow made the status of the Dillingham runway unknown and its condition was a concern. On the ground in King Salmon, the crew contacted Kenai Flight Service and requested any updated runway conditions at the next destination. There was no update and flight 51 departed King Salmon at 7:55 a.m.

According to the NTSB investigation, the air traffic controller at Anchorage Center who handled flight 51's departure from King Salmon was relieved by another controller at 8:00 a.m., while the flight was still en route to Dillingham. He briefed his replacement on the status of the five aircraft in their sector prior to leaving. At about 8:04 a.m., flight 51 made its request for clearance to an instrument approach to Dillingham viaa point identified on charts as Zedag, the initial approach fix.The aircraft was then flying at about 6,000 feet.

At that point, the new controller approved the request and directed the crew to “maintain at or above 2,000" feet until established on a published segment of the approach. The published minimum altitude when approaching Zedag from the direction of King Salmon is 5,400 feet, and the altitude at the approach fix is 4,300 feet due to rising terrain in the area. The ambiguous nature of the clearance -- “until established on a published segment” -- and the flight crew’s slightly altered read back to “maintain 2,000” until established, led the NTSB to determine this communication was a factor in the crash.

The controller told the NTSB that “he did not expect the aircraft to descend below 5,400 feet, and did not notice when the pilot did so.” Other controllers and supervisors gave conflicting opinions on how they felt about the clearance. One referred to it as “not good” and another stated it was a “bad clearance.” Still, another said that while the accident sequence was unfortunate, in his opinion, “the crew was trying to cut corners.”

As flight 51 continued to the initial approach fix, the aircraft’s altitude sparked a warning from the automated Minimum Safe Altitude Warning system in ATC. This warning, characterized by a visual display and an audible series of short beeps that sound for one second, is designed to inform the controller that an aircraft is in danger of colliding with the surrounding terrain. The ATC controller communicating with flight 51 ignored the warnings, which remained active during his final transmission with the flight crew.

In his interview with the NTSB, the controller said that “he was not consciously aware that the MSAW alert was going off,” and that “The frequent MSAW nuisance alarms conditioned controllers to not be as attentive as they otherwise would be.”

This “alarm fatigue” was echoed by others in ATC who told the NTSB it was “quite common to hear aural alarms in the control room”, and that the system “generates frequent warnings, and many of them are invalid.” One supervisor countered that conclusion however, asserting that “all MSAW alerts should be evaluated and a safety alert issued if warranted.”A second discounted the belief that MSAWs were nuisances, saying that “most were valid.” He professed "shock" that there had been no response to the flight 51 MSAW alert.

While communicating with ATC, flight 51 was still trying to ascertain the condition of the Dillingham runway. At 8:07 a.m., the flight crew contacted flight service there, and one minute later was in touch with flight service personnel and the truck that was going out to physically check on the runway. The driver, who was heading for the active runway, asked for an estimated time on flight 51’s arrival. The flight crew offered to hold and at 8:09 a.m. made its last transmission to ATC requesting a hold at Zedag, which was immediately approved. No one spoke with flight 51 again.

Concerns with FAA oversight

As a scheduled air carrier operating under part 135 of the Federal Aviation Regulations, ACE is assigned FAA safety inspectors. The operations inspector is specifically tasked with such things as evaluating pilot competence, company flight training programs and operations to ensure safety and compliance with regulations. Typically inspectors work closely with companies, but it's clear from the NTSB interview that there was a disconnect between ACE’s operations inspector and the company. Further, according to the investigation, the ACE operations inspector was also responsible for oversight of another large part 135 operator, several flight schools, Part 91 operators and the designated pilot examiners in the Anchorage District.

According to the NTSB report, at the end of January 2013, ACE’s Director of Operations, a management position requiring FAA approval, resigned and notified their ops inspector by telephone. He subsequently submitted a letter of request for another employee to be made acting DO. He assumed this request -- not uncommon in the industry -- was accepted until the morning of the accident when the inspector contacted him and requested he resume his former job, becausethe acting DO did not currently meet the position’s regulatory requirements. During an NTSB interview, the inspector displayed no knowledge of the former’s DO’s resignation, revealing a lack of involvement with ACE “from the end of January 2013, and extending to March 10[sic], the day of the accident.” It was possible the inspector might have forgotten the phone call, but “could not recall,” the NTSB report said.

As the interview continued, it was made clear the inspector never observed Crew Resource Management (or CRM) training at ACE, which would have provided the FAA with insight into how flight crews were trained to work together. The inspector professed no knowledge to the NTSB of how ACE conducted operational control over its flights and further had no training or experience in the Beech 1900. Because of this, another inspector from the Anchorage office was identified in the report as the person required to conduct pilot checkrides in the aircraft. It is unclear why the FAA assigned an inspector to ACE who had never been qualified to fly in the only aircraft the company operates.

CRM training was developed to prevent human errors and emphasize crew interactions, which are critical to flight safety. In the case of flight 51, effective communication in the cockpit would likely have addressed any confusion presented by the ATC clearance and reinforce company procedures. According to the report, Alaska Central Express requires that the pilot who is flying briefs the approach and both crew members are supposed to have the approach plate open on their control yoke. It is unknown why this communication apparently did not take place. The failure of the flight crew to follow procedures was cited as a factor in the accident by the NTSB.

Lost opportunities to prevent accident

The ATC controller told the NTSB that “informing the pilot of his position in reference to the initial approach fix was not required.” The crew of flight 51 however, appears to have been preoccupied with Dillingham runway conditions; they appear not to have noticed the discrepancy between the altitude instructions and their position, as they should have. This is why redundancies are built into the air traffic control system and why flight crews read back instructions -- so ATC can catch and prevent any miscommunications.

The MSAW system exists to alert ATC when a potentially dangerous situation occurs so they can then alert a flight crew. CRM teaches pilots to work together to avoid and solve problems before they become unrecoverable. The FAA is tasked with effective air carrier oversight so it can contribute its vast resources to supporting the best learning environment possible.

As the probable cause report makes clear, mistakes were made by multiple people on the ground and in the air. Unfortunately, the aircraft was not equipped with an optional voice recorder or cockpit image recording technology. The image technology in particular would have provided a visual of what took place inside the aircraft and without it the NTSBdoes not have critical information from the cockpit.

“It would tell us a great deal about the human factors involved here,” said Clint Johnson, chief of the NTSB Alaska Region. “All we can do is theorize what was going on in the cockpit and without that information, I feel that a golden opportunity has been missed to learn from this tragedy. As the plaque at the NTSB Training Center recites, 'from tragedy we draw knowledge to improve the safety of us all.'"

With the release of the probable cause report, factual narrative and public docket, the final documents on the crash of Alaska Central Express flight 51 have all been filed. Jeff Day and Neil Jensen are now just one more part of Alaska’s long tragic aviation record. According to the FAA, the employee who provided them with those questionable instructions out of King Salmon is still listed as a controller in the state of Alaska. The operations inspector who oversaw ACE at the time of the accident has since relocated to another office out-of-state.

What can be learned from flight 51 moving forward is up to the entire Alaska aviation community. Its members will have to think long and hard about how much it matters to fully understand what took place on the way to Dillingham on March 8, 2013, and what can be taught, both on the ground and in the air, to make sure such a tragedy never happens again.